Drainage Report

Groundwater Recharge A | a S Anderson Consulting Services LLC Groundwater recharge is achieved through the sand bottom in the small-scale infiltration basins. The 2 year storm volume routed to the basin is recharged. A separate routing has been performed for the 2 year storm to determine the volume of recharge for this drainage area. Test pits B1 &B1 were excavated to a depth of 13ft and 15 ft with groundwater located at 8 and 9 feet below grade. Based on the surface grade at the test locations the groundwater elevation is elevation 538 The basing bottom is set at elevation 540.0 making any groundwater in this area in excess of 2 ft below the bottom of the basin. The permeability of B2 was determined to be .89 in/hr. With a factor of safety of 2 the exfiltration rate from the basin used in the hydrocad calculation was .45 in/hr. A summary spreadsheet for the groundwater recharge on the project is provided on sheet 14 Infiltration basin is listed as a green technology solution for groundwater recharge with pre-treatment provided. Detention Basin 3 Area Detention basin 3 collects water from the clubhouse and building A along Warner Road. The Existing Area of Basin 3 contributing area is 113995 sf of Woods in good condition. The initial 100 LF is sheet flow with a slope of 4% in woods with light underbrush. Tc=15.7 min The next segment is shallow concentrated flow 204 If with a slope of 3.7% through woods with light underbrush. There is no discernable channel in the field along this path that would change the categorization of the flow type. Tc = 19.4 min. Proposed Tc - Sheet Flow 100 LF @8% grass cover Tc= 7.9 min Shallow concentrated flow 20 If @ 8% Tc=..1 min, grass cover Shallow Concentrated Flow 100 LF@ 5% Tc =.4 min, Pavement Cover Pipe Flow 450 If of 15 inch pipe @ 6% N=0.01 Tc.8 min Total Tc= 9.2 min Un-detained Area associated with Basin 3. These are small areas at the perimeter of the drainage area that have minimal distance to travel before exiting the area of analysis. The longest path is Sheet flow 45 If @ 10% over grass Tc= 3.8 min Detention basin 3 collects water from the center of the site from the clubhouse down proposed Warner Rd. that drains to the Canoe Brook Tributary. The existing conditions have been modeled with a coverage as wood is good condition as required by the standards with NOAA type D rainfall curves. The table

. that drains to the Canoe Brook Tributary. The existing conditions have been modeled with a coverage as wood is good condition as required by the standards with NOAA type D rainfall curves. The table below outlines the results of the routing for this area. 7 Anderson Consulting Services LLC 40 Miller Drive, Boonton, NJ 07005 973-975-0703 (O) 973-886-7336 (C) PAndersonpe@gmail.com